The family of a mentally-ill man who died while in police custody have called for the officers involved to face court.

Gwent Police has been criticised by an official watchdog following the death of Andrew David Sheppard, who was detained at Newport Central Police Station after behaving irrationally.

The 22-year-old was found to have cocaine and other drugs in his system and forensic analysis suggested he had taken some of the substances while in custody.

Following an inquest into his death, the Independent Police Complaints Commission (IPCC) published a report saying police had failed to protect Mr Sheppard from harm.

One custody sergeant was fined 13 days’ pay and three custody sergeants reprimanded. Four custody detention officers received management advice, along with one of the police constables who detained Mr Sheppard.

His family say that while they were pleased it had been officially recognised how Mr Sheppard had been failed by police, they wanted charges pressed.

A statement read: “We are relieved the jury has recognised how badly Andrew was failed by Gwent Police. The police officers who let Andrew down should now face criminal prosecution on the basis of the new evidence heard at the inquest.”

Mr Sheppard had been behaving irrationally on September 30, 2006, and he and his family had been in contact with the police and health professionals on several occasions during that day to seek advice.

He was later detained by officers under Section 136 of the Mental Health Act 1983 and taken to Newport Central Police Station.

An inquest heard that despite police being on notice that Mr Sheppard was at risk of a drugs overdose, he was not properly searched while being detained overnight at the station.

The following day officers went to Mr Sheppard’s cell so he could be medically assessed by a police surgeon.

The custody officer was concerned about Mr Sheppard’s condition and called for assistance.

Mr Sheppard was later taken to the Royal Gwent Hospital, but never regained consciousness.

A jury at his inquest ruled there had been “gross failings” in the system.

The IPCC commissioner for Wales Tom Davies said: “Andrew Sheppard was a very troubled young man. Once Mr Sheppard had been detained by the police and taken to what is known as ’a place of safety’ he was owed a duty of care by the custody staff. It was clear from his own admission, plus information known to the police, that he was vulnerable.

“Those custody staff for a variety of reasons did not keep proper records, did not check on Mr Sheppard with the frequency they should have done, and nor did they keep him under proper observation.”

Mr Davies added it was likely Mr Sheppard had taken an overdose of painkillers while in a CCTV observation cell at the police station.

He said: “We have said on numerous occasions custody is the wrong place for somebody with mental health problems and who invariably may also have taken substances, but we accept that sometimes it is the only place available.

“But when a vulnerable person like Andrew Sheppard is taken into custody we do expect the measures outlined in the Police and Criminal Evidence Act codes of practice for dealing with detainees are applied by custody staff.

“Expert forensic analysis showed in all probability Mr Sheppard had taken drugs during the time he was in custody, which shows how poor the observation of him had been that night.

“Evidence from our investigation led to one custody sergeant being fined 13 days pay and three custody sergeants reprimanded. Also, four custody detention officers received management advice, along with one of the police constables who detained Mr Sheppard.”

The IPCC made eight recommendations to Gwent Police about its custody policy, which it said had been implemented since Mr Sheppard’s death.